Removal of acetic acid in mulberry wine by co-inoculating Saccharomyces cerevisiae with indigenous non-Saccharomyces yeast

Abstract

Excessive levels of acetic acid in fruit raw materials can significantly compromise the sensory quality of the final wines. The aim of this study was to isolate non-Saccharomyces yeasts capable of metabolizing acetic acid in fruit juices, and to evaluate their enological potential in mulberry winemaking. A synthetic medium and mulberry juice were used as fermentation media, respectively. Results showed that Pichia barkeri S29 reduced the final contents of acetic acid in the synthetic medium much lower than Saccharomyces cerevisiae RV002, and addition of 2 g/L acetic acid in the synthetic medium enhanced the ethanol productivity of P. barkeri S29. In mulberry wines, P. barkeri S29 reduced roughly 43 % of the acetic acid in mulberry juice, while S. cerevisiae RV002 increased the final acetic acid level by 1.4-fold. Although mixed fermentation with P. barkeri S29 and S. cerevisiae RV002 inhibited the vitality of P. barkeri S29, the concentration of acetic acid in wines declined by 65 %–73 % compared to pure fermentation of S. cerevisiae RV002. Furthermore, mixed fermentation boosted the variety and concentration of ester compounds, including ethyl decanoate, ethyl dodecanoate, and ethyl hexadecanoate, potentially improving the fruity flavors of mulberry wines.